Chemical Sensors Based on Molecularly Imprinted Polymers Can Determine Drug Release Kinetics from Nanocarriers without Filtration, Centrifugation, and Dialysis Steps.

With the development of drug delivery systems, the use of nanomaterials for slow, targeted, and effective drug release has grown significantly. To ensure the quality of performance, it is essential to obtain drug release profiles from therapeutic nanoparticles prior to in vivo testing. Typically, the methods of monitoring the drug release profile from nanoparticle drug delivery systems include one or more filtration, separation, and sampling steps, with or without membrane, which cause several systematic errors and make the process time-consuming.

Mediator-Free Self-Powered Bioassay for Wide-Range Detection of Dissolved Carbon Dioxide.

Electrochemical sensors for the dissolved CO (dCO) measurement have attracted great interest because of their simple setup and the resulting low costs. However, the developed sensors suffer from the requirement of the external electrical power supply throughout the sensing. Here, the fabrication and evaluation of a self-powered biosensor based on biofuel cells (BFCs) for dCO measurements are described.

A novel aptasensing method for detecting bisphenol A using the catalytic effect of the FeO/Au nanoparticles on the reduction reaction of the silver ions.

The gold electrode was functionalized with anti-bisphenol A (BPA) aptamer and captured the BPA as analyte. By dropping the aptamer-modified magnetic FeO/Au nanoparticles solution onto the electrode, a BPA molecule attaches to many aptamers that are in contact with a large number of FeO/Au nanoparticles. The modified electrode were transferred to a solution containing Ag ions.

Efficient immobilization of aptamers on the layered double hydroxide nanohybrids for the electrochemical proteins detection.

Despite the use of layered double hydroxides (LDH) in different electrochemical (bio)sensors, the construction of aptasensors using LDH-based surfaces was not reported to the best of our knowledge. This may be due to the lack of a suitable linker to attach aptamers to the LDH-modified surface. LDH-based aptasensors are established here as very sensitive and reliable devices in serum and cerebrospinal fluid (CSF) analysis.

Impedimetric aptasensing of the breast cancer biomarker HER2 using a glassy carbon electrode modified with gold nanoparticles in a composite consisting of electrochemically reduced graphene oxide and single-walled carbon nanotubes.

A method is presented for electrochemical determination of the breast cancer biomarker HER2. A glassy carbon electrode (GCE) was modified with densely packed gold nanoparticles placed on a composite consisting of electrochemically reduced graphene oxide and single walled carbon nanotubes (ErGO-SWCNTs). An aptamer directed against HER2 was then immobilized ono the GCE.

A glassy carbon electrode modified with TiO(200)-rGO hybrid nanosheets for aptamer based impedimetric determination of the prostate specific antigen.

TiO(200)-rGO hybrid nanosheets were synthesized starting from TiO, rGO and NaOH solid powders via a scalable hydrothermal process. The weight ratio of TiO-GO was found to be crucial on the crystal growth and biosensor properties of the final hybrid nanosheets. They were characterized by means of SEM, FESEM-EDX, XRD, XPS, Raman and FTIR spectroscopies in order to verify the formation of very thin TiO anatase nanosheets with an orientation of the anatase crystal structure towards the (200) plane.

Electrochemical bioassay development for ultrasensitive aptasensing of prostate specific antigen.

A densely packed gold nanoparticles on the rGO-MWCNT platform was used as the basis for an ultrasensitive label-free electrochemical aptasensor to detect the biomarker prostate specific antigen (PSA) in serum. The detection was based on that the variation of electron transfer resistance (R) and differential pulse voltammetry (DPV) current were relevant to the formation of PSA-aptamer complex at the modified electrode surface. Compared with pure AuNPs, rGO-MWCNT and MWCNT/AuNPs, the rGO-MWCNT/AuNPs nanocomposite modified electrode was the most sensitive aptasensing platform for the determination of PSA.

An electrochemical aptasensor based on TiO2/MWCNT and a novel synthesized Schiff base nanocomposite for the ultrasensitive detection of thrombin.

A sensitive aptasensor based on a robust nanocomposite of titanium dioxide nanoparticles, multiwalled carbon nanotubes (MWCNT), chitosan and a novel synthesized Schiff base (SB) (TiO2/MWCNT/CHIT/SB) on the surface of a glassy carbon electrode (GCE) was developed for thrombin detection. The resultant nanocomposite can provide a large surface area, excellent electrocatalytic activity, and high stability, which would improve immobilization sites for biological molecules, allow remarkable amplification of the electrochemical signal and contribute to improved sensitivity. Thrombin aptamers were simply immobilized onto the TiO2-MWCNT/CHIT-SB nanocomposite matrix through simple π - π stacking and electrostatic interactions between CHIT/SB and aptamer strands.

Electrochemical study of quinone redox cycling: A novel application of DNA-based biosensors for monitoring biochemical reactions.

This paper presents the results of an experimental investigation of voltammetric and impedimetric DNA-based biosensors for monitoring biological and chemical redox cycling reactions involving free radical intermediates. The concept is based on associating the amounts of radicals generated with the electrochemical signals produced, using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). For this purpose, a pencil graphite electrode (PGE) modified with multiwall carbon nanotubes and poly-diallydimethlammonium chloride decorated with double stranded fish sperm DNA was prepared to detect DNA damage induced by the radicals generated from a redox cycling quinone (i.

Determination of atropine sulfate using a novel sensitive DNA-biosensor based on its interaction on a modified pencil graphite electrode.

A novel, selective, rapid and simple electrochemical method is developed for the determination of atropine sulfate. UV-Vis and differential pulse voltammetry are used to study the interaction of atropine sulfate with salmon sperm ds-DNA on the surface of salmon sperm ds-DNA modified-pencil graphite electrode (PGE). For this purpose, a pencil graphite electrode (PGE) modified with multiwall carbon nanotubes (MWCNTs), titanium dioxide nanoparticles (TiO2NPs), and poly-dialyldimethylammonium chloride (PDDA) decorated with ds-DNA is tested for the determination of atropine sulfate.

Redox targeting of DNA anchored to MWCNTs and TiO2 nanoparticles dispersed in poly dialyldimethylammonium chloride and chitosan.

A key issue associated with electrochemical DNA-based biosensors is how to enhance DNA immobilization on the substrates. In order to improve the immobilization of DNA and to optimize DNA interaction efficiency, different kinds of strategies have been developed. In this regard, nanomaterials have attracted a great deal of attention in electrode surface modification for DNA biosensor fabrication.

Improved immobilization of DNA to graphite surfaces, using amino acid modified clays.

Assessment of the interaction of small molecules with DNA, hybridization assays for DNA sequence analysis and diagnostics and the investigation of DNA damage involves the immobilization of an array of oligonucleotides onto a solid substrate. Herein, a new nano sized DNA-based biosensor containing valine (Val) amino acid organo-modified Cloisite Na as a new bionanohybrid film for the immobilization of DNA was developed. The Cloisite-Val organoclay was synthesized by a cation-exchange method, which involves the displacement of the sodium cations of Cloisite Na with the ammonium ions of the Val-amino acid.

DNA-based biosensor for comparative study of catalytic effect of transition metals on autoxidation of sulfite.

The transition metal-catalyzed oxidation of sulfur(IV) oxides has been known for more than 100 years. However, to the best of the authors' knowledge, no electrochemical quantitative study has yet been carried out to determine its nature. In view of the transition metal catalyzed oxidation of sulfur(IV) oxides, a series of radicals are involved in the overall reaction process whereby the sulfite, in the presence of transition metals, may cause damages to DNA through the generation of these highly reactive species.

A novel sensitive DNA-biosensor for detection of a carcinogen, Sudan II, using electrochemically treated pencil graphite electrode by voltammetric methods.

A simple and inexpensive methodology was used to develop a novel electrochemical sensor for the determination of Sudan II. The interaction of Sudan II with salmon sperm ds-DNA on the surface of salmon sperm ds-DNA-modified pencil graphite electrode (PGE) and in solution phase was studied, using differential pulse voltammetry. The difference between adenine and guanine signals of the ds-DNA after and before interaction with Sudan II was directly proportional to Sudan II concentration, which used for quantitative inspections.

DNA-functionalized biosensor for riboflavin based electrochemical interaction on pretreated pencil graphite electrode.

The interaction of riboflavin with salmon sperm double-stranded DNA based on the decreasing of the oxidation signal of guanine and adenine bases was studied electrochemically with a pencil graphite electrode (PGE) using differential pulse voltammetry. The decrease in the intensity of the guanine and adenine oxidation signals after interaction with riboflavin was used as an indicator signals for the sensitive determination of riboflavin. Under the optimum conditions, a linear dependence of the guanine and adenine oxidation signals was observed for the riboflavin concentration in the range of 0.